In recent years, packaging materials and containers have been manufactured by molding metal laminate films. A metal laminate film includes a resin layer (containing polyamide, polypropylene, and PET) laminated on a metal thin film (containing aluminum, copper, and iron). A technique for molding such a metal laminate film is also applied to a processing technique of manufacturing packages for nonaqueous electrolytic secondary batteries and packages for other secondary battery packages.
When a metal laminate film as a material is molded into a deep shape, the metal laminate film may have breaks or slightly or considerably wavy wrinkles on or around a molded portion.
Such breaks may expose an interior product to an external environment, interfering with the protective function of a package. Moreover, such wrinkles may spoil the appearance of the package and have a repeated stress concentration caused by frictions with the external environment, temperature changes, and so on. Thus, fatigues are accumulated with the passage of time so as to accelerate breaks on the film. For this reason, there is a need for a method for molding a metal laminate film so as to simultaneously suppress breaks and wrinkles.
FIG. 12 illustrates a conventional technique for attaining the object.
FIG. 12(a) is a cross-sectional view illustrating an assembly of a cope and a drag. FIG. 13(a) is a plan view of the cope taken along line A1-A1 of FIG. 12(a). FIG. 13(b) is a plan view of the drag taken along line A2-A2 of FIG. 12(a). A die 1 serving as the drag has a die hole 1a. The cope includes a punch 2, a plate 4, and an elastic body 51.
In the technique illustrated in FIGS. 12(a) and 12(b), the die 1, the plate 4, and the elastic body 51 apply a pressure to an area 3b surrounding a metal-laminate-film molded portion of a metal laminate film 3, which is a workpiece. The die 1 is opposed to the punch 2 while the plate 4 and the elastic body 51 are provided around the punch 2.
In this configuration, a pressure applied to the metal laminate film 3 by the elastic body 51 is smaller than a pressure to the plate 4. A pressure applied to the metal laminate film 3 by the plate 4 is set so as to completely fix the metal laminate film 3 on the top surface of the die 1. Thus, the metal laminate film 3 pressed by the elastic body 51 and the plate 4 is molded into a desired shape by pressing the punch 2 into the die 1. In this case, the elastic body 51 applies a proper pressure to the metal laminate film 3, thereby suppressing the occurrence of wrinkles while accelerating a flow of material into a molded portion 3a. 